Endless carrier printer

ABSTRACT

A plurality of printing pallets have a plurality of type members secured on the inner end portions of shanks which are removably mounted in uniformly fashioned and spaced apertures extending transversely of an endless carrier, therey enabling type replacement in the printer. The upper edges of sides forming a fixed channel disposed below the upper course of the carrier are disposed at a level for engaging the inner and outer end portions of the shanks and adjusting the type faces vertically for printing. Gross positioning of the pallets in a path transversely of the carrier is effected by a pair of opposed bosses disposed at opposite sides of the carrier for engaging the type members and the shanks. Fine or final positioning of type faces in printing positions transversely of the carrier is achieved by printing action which drives the outer ends of the shanks against a backstop.

United States Patent [1 1 Huntoon et al.

[ ENDLESS CARRIER PRINTER [75] Inventors: Francis E. Huntoon, Des Plaines;

James F. Kearney, Oak Park, both of I11.

' [73] Assignee: Teletype Corporation, Skokie, Ill.

22 Filed: Dec. 15, 1971 211 Appl. 190.; 208,198

3,041,964 7/196 2 Simpson et a1. 101/111 3,041,965 7/1962 Sasaki 101/111 3,142,249 7/1964 Sasaki 101/111 3,216,348 11/1965 Oldenburg et a1. 101/93 C 3,353,483 11/1967 Foley 101/93 C 3,435,756 4/1969 Martin 101/93 C 3,499,382 3/1970 Potter et a1. 101/93 C 3,653,321 4/1972 Cunningham 101/93 C OTHER PUBLICATIONS IBM Technical Disclosure Bulletin, Vol. 10 No. 3 Aug.

[ July 3,1973

Primary Examiner-William B. Penn AttorneyJ. L. Landis et a1.

[5 7] ABSTRACT A plurality of printing pallets have a plurality of type members secured on the inner end portions of shanks which are removably mounted in uniformly fashioned and spaced apertures extending transversely of an endless carrier, therey enabling type replacement in the printer. The upper edges of sides forming a fixed channel disposed below the upper course of the carrier are disposed at a level for engaging the inner and outer end portions of the shanks and adjusting the type faces vertically for printing. Gross positioning of the pallets in a path transversely of the carrier is effected by a pair of opposed bosses disposed at opposite sides of the carrier for engaging the type members and the shanks. Fine or final positioning of type faces in printing positions transversely of the carrier is achieved by printing action which drives the outer ends of the shanks against a backstop.

14 Claims, 6 Drawing Figures PATEN TED JUL 3 I975 SMUIUFZ ENDLESS CARRIER PRINTER FIELD OF THE INVENTION The present invention relates to signal controlled impact printing machines. Particularly, it relates to printers having an endless carrier for type dies of printable symbols or characters adapted for printing by percussion.

Printers of the class with which the present invention is concerned are exemplified in E. R. Wooding US. Pat. No. 2,918,865, herein incorporated by reference. They are generally known as belt or chain printers; and have simple yet effective mechanical combinations. Widespread utilization of these printers, in the low cost market has been curtailed, however, notwithstanding their assets as printers, because of the high cost of logic for driving the impactors to generate printer output at an acceptable speed. Improvements in micro minature circuit technology have enabled cost reductions such that interest in belt or chain printers for commercial exploitation has recently again come of interest.

It is an object of the present invention to provide an improved printer of the indicated class.

It is another object of the invention to print inexpen' sively with such printer.

Further objects of the invention are to enable printing with replaceable type members in a printer of such class, and to provide for precise positioning of the type members.

SUMMARY OF THE INVENTION The foregoing, and other objects of the invention which will become apparent from the ensuing detailed description, are realized, according to one aspect of the invention, in an impact printer of the class wherein a plurality of type faces are arranged from an endless carrier. The carrier is entrained about spaced apart rollers for movement longitudinally of a circuitous path, in a printing course of which the type faces are aligned with impactor means for printing. The carrier also has a plurality of longitudinally and uniformly spaced transverse openings. A plurality of type-carrying elements are mounted for movement in said openings, respectively, for removing the type faces from the carrier.

Another feature of the invention relates to a mechanism for precise vertical positioning of the type members, particularly, using an elongated horizontal rail for engaging portions of the type members to position them for printing.

BRIEF DESCRIPTION OF THE DRAWINGS In the ensuing detailed description of the invention, reference is had to the accompanying drawings on which:

FIG. 1 is a scheme, in perspective, of a printer embodying the invention, portions of a web arranged for printing being broken away;

FIG. 2 is a top plan view of a segment of the belt of said printer according to the line 2-2 of FIG. 1, parts of the belt being broken away, and a hidden part being shown in dashed lines;

FIG. 3 is a side view of the belt according to the line 3--3 of FIG. 2, portions of a back stop being omitted,

and a hidden part being shown in dashed lines;

FIG. 4 is an end view of the printer according to the line 4-4 of FIG. 3, portions of the belt being broken away;

FIG. 5 is an enlarged detailed view of a segment of the belt in its upper course and looking toward a side thereof, a hidden part being shown in dashed lines; and

FIG. 6 is a detailed view of the belt according to lines 6-6 of FIG. 5, a die assembly being omitted.

DETAILED DESCRIPTION OF THE ILLUSTRATED EMBODIMENT Referring now more particularly to the drawings, shown is only sufficient of impact printer It) for illustrating the invention. The printer is of the class which has an endless carrier, herein shown as a belt 12, trained about and supported by a pair of horizontally spaced apart rollers 14 and I6 (FIG. I) in a vertical plane. The rollers are suitably journalled on the frame (not shown) of the printer with their axes of rotation parallel and extending horizontally perpendicular to the plane of belt 12 such that an upper or printing course 18 and a lower or return course 2 are provided in the circuit of the belt.

Herein, rollers I4 and 16 are shown as sprocket wheels with sprockets 21 (FIG. 1) proportioned operably to mesh or engage in recesses 22 (FIG. 5) between equally spaced apart lugs 23 fashioned longitudinally of belt 12. Roller 14 is shown as an idler while roller 16 is shown as a driver. The latter is mounted on a shaft 24 which is coupled to prime mover means (not shown) through agency of a gear 26 for driving the belt continuously in a circuitous path; for example, in a clockwise direction as viewed in FIG. I.

The belt is tensioned as by urging the idler roller 14 away from the drive roller 16 (to the left in FIG. 1) with a constant force; for example, eight pounds. This belt tensioning maintains alignment of the belt and cooperates in precise vertical positioning of a plurality of type pallets 28, as will be explained hereafter. Preferably, the idler roller 14 is mounted for movement toward and away from the drive roller 16 to permit this tensioning, and to allow for belt replacement when desired.

The pallets 2% have type faces 29 (FIG. 4), which may be fashioned as one or more fonts of alphanumeric characters or other symbols, and are carried from belt 12, the pallets being equally spaced apart longitudinally of the belt. The spacing of the pallets is such that during operation of the printer 10, successive sections of the belt in upper course I8 will travel past and be aligned horizontally with a plurality of uniformly spaced apart impactors 30 in a horizontal array thereof comprising impactor means. As the successive printing die assemblies 28 travel with the belt 12 past the impactors in the printing course 18 (from left to right in FIG. 1), selected impactors 30 are operated to print the various type characters in a desired sequence, generally as disclosed in the Wooding patent, while the die assemblies are moving.

Each impactor 30 is adapted for reciprocation horizontally in a path perpendicular to upper course 18 between a non-printing aspect and a printing aspect. A rod 31 fixed to the printer frame (not shown) and extending through a plurality of aligned slots 32 in the impactors limits impactor movement in opposite directions between their printing and non-printing aspects.

As any impactor 30 moves into its printing aspect (toward the front in FIG. ll), a web 34 or paper to be printed is struck thereby from behind, for driving the forward web face 36 against an inked ribbon 38 and with sufficient force for impressing an image from the aligned type face 29 on said forward web face, all in a manner which may be conventional.

The details of construction of means for controlling the reciprocation and the sequence of operation of impactors 30 and movement of belt 12 to align a selected type face with an impactor form no part of this invention. Similarly, the details of construction of means for controlling movement of ribbon 38 form no part of the present invention and accordingly, only opposed spool housings 40 and 42, which may be of conventional construction and to which opposite ends of the ribbon are connected, are shown.

Exemplary means for feeding web 34 from a coil 44 thereof, which may be supported by the printer frame (not shown), comprises a cylinder or roller 46 which engages the back web surface 47 for frictionally drawing the web upwardly in the direction indicated by arrow 48. A pinch roller (not shown) may be arranged for holding the web in frictional engagement against cylinder 46. A pulley wheel 50, which is secured on shaft 52 of the cylinder 46 is driven by prime mover means (not shown) through the agency of a pulley belt 54 for moving the web preferably in step-by-step increments after each line has been printed as is generally conventional in the printing art and termed line feed.

According to the present invention, the belt 12 has a plurality of uniformly fashioned openings or apertures 56 (FIGS. 4, 5, and 6) for mounting pallets 28. The apertures are equally spaced apart longitudinally of the belt circuit, and set the desired spacing between die assemblies when the belt 12 is stretched tight in running condition. The openings or apertures extend horizontally through the belt from the outside or web distal side 57 (FIGS. 2, 4, and 6) to the inside or web proximate side 58 and perpendicular to the belt circuit. The openings 56 preferably are rectangular in crosssection (FIG.

The pallets 28 include a plurality of elements herein comprising elongated shanks 60 which are mounted for movement longitudinally of their axes in transverse openings 56. Said shanks preferably are rectangular in cross-section to conform to the preferred crosssectional configuration of said openings; and each has an outer end portion 62 projecting axially away from the web distal side 57 of the belt and an inner end portion 64 projecting from the web proximate side 58 of belt 12. A type member 66, on which each type face 29 is formed, is secured on or connected to the belt distal end of each inner end portion 64. Each type member 66 and its shank 60 comprise a pallet 28.

The heights and widths of the shanks 60 in crosssection (FIG. 5) preferably are the same as the heights and widths of openings 56. The dimensions are such that said shanks are frictionally gripped and lightly restrained from transverse movement. However, the restraining force will yield to intentional manual force for enabling slideable movement of the shanks in said transverse openings for removing pallets 28 from belt 12. Thereby, pallets may be selectively replaced such that a type face 29 formed in one symbol or style may be substituted for another type face formed with another symbol or in another style.

A rigid backstop or abutment member 68 (FIGS. 2, 3, and 4) is supported from the frame (not shown) of printer 10 by any suitable means adjacent upper course 18 of belt 12 on a side 57 of said belt opposite the array of impactors 30. The backstop has an inner or web proximate straight surface 69 which is disposed in a vertical plane, parallel to the sides 57 and 58 of the belt, and adjacent the outer end portions 62 of the shanks 60. The arrangement and proportioning of parts is such that, when said outer end portions are engaged with surface 69, the die assemblies 28 are in a desired horizontal position transversely of the belt for printing.

A boss 70 (FIG. 3) projects along side 57, in a vertical plane, upstream from backstop 68 with which said boss is integrally fashioned and preferably curves downward as shown in FIG. 3. The boss is disposed adjacent roller 14 and has a feed-in taper or slope 71 when considered in a horizontal aspect (FIG. 2). The taper slants beltwardly to straight edge 69 as it extends downstream so as to shift or cam the shanks 60 to the left in FIG. 4 to the desired printing position against the surface 69, if any die assemblies have shifted too far to the right in FIG. 4 during the travel along the return course 20. Boss 70 also has an arcuate configuration 72, when viewed in a vertical plane (FIG. 3), which has a radius of curvature substantially equal to the radius of curvature of belt 12 as it moves about roller 14 from the lower course into the upper course. This configuration aligns boss 70 with end portions 62 of shanks 60 as they move about roller 14 into said upper course.

Another boss 74, with an accurate configuration when viewed in a vertical plane (FIG. 3), is rigidly secured to the frame (not shown) of printer 10 in horizontal alignment with the arcuate configuration 72 of boss 70. However, boss '74 is disposed at the inner or printing side 58 of belt 12. Boss 74 has a working, inner, or belt proximate surface 75 with a straight portion 76 parallel to sides 57 and 58 and a lead-in position 78 sloped beltwardly as it projects downstream. Surface 76 is disposed such that it will engage a type member 66 which projects too far ribbonward, forcing or camming it back toward backstop 68.

By reason of the foregoing construction, pallets 28 are substantially self-aligning in course 18 and transversely of belt 12. To appreciate this concept, assume a font of die assemblies has been replaced or inserted in belt 12 for the first time. An operator need not concern himself with fine positioning thereof transversely of the belt. Gross placement of the assemblies with respect to desired rotation transversely of the belt is changed to a gross adjustment through the agency of bosses 70 and 74. Final, or fine, positioning of a die assembly results from its first operation with an impactor 30. That is to say, the operative force of an impactor for printing is adapted to drive a die assembly against surface 69 of the backstop 68. Once that has been done, such die assembly will be and remain properly aligned transversely of belt 12 for printing.

In the illustrated embodiment, belt 12 is fabricated from an elastomeric composition, such as polyurethane. To prevent stretching of the belt longitudinally, a plurality of strands 80 (FIGS. 5 and 6) of any suitable fabrication, such as fiberglass, may be embedded in the belt running in the direction of movement. The elasticity of the belt, however, accommodates movement of the shanks 60 within apertures 56 as the belt moves about rollers 14 and 16 without substantial shift in the relative positions of the belt 12 and the pallets. Moreover, the belt elasticity, particularly compressibility of the walls of apertures 56 facilitate pallet replacement.

Although apertures 56 are arranged and belt 12 is proportioned for maintaining selected spacing of pallets 28 for which the belt serves as a carrier, the belt is not principally involved in vertical positioning of said assemblies for printing. In accordance with the present invention, means for vertically positioning pallets 28 and accordingly, type faces 29, while in printing course 18, comprise the horizontal upper straight edges 86 and 88 (FIGS. 2 and 4) of vertical sides or rails 90 and 92 of a U-shaped camming member or channel 94. The channel is ridigly secured on the frame (not shown) of printer and is disposed between said upper course and lower course (FIG. 1), with an upper opening 96 which faces the upper course 18 of belt 12. The

edges 86 and 88 extend longitudinally of said upper course and have horizontal alignment transversely of their lengths. Said edges are spaced apart a distance such that they engage respectively outer and inner end portions 62 and 64 of each shank 60 when in the print ing course of belt 12, for holding said assemblies at the selected height for printing. Channel 94 extends substantially the length of the entire upper course 18 between rollers 14 and 16 and is proportioned for accommodating passage therethrough of lugs 23 of the belt while in said upper course.

Channel 94 has a pair of upstream extensions 98 and 100. They are disposed about opposite faces of roller 14. The extensions have upper edges 102 and 104 (FIGS. 2 and 3) which are upstream extensions of edges 98 and 100. Edges 102 and 104 are arranged for engaging and supporting shanks 60 as die assemblies 28 'move downstream off of roller 14. Each of the edges 102 and 104 has a lead-in taper which slants upwardly as it extends downstream toward its respective edge 86 or 88. With this arrangement, the tapered edges 102 and 104 lift the shanks 56, and with them the entire flexible belt 12, slightly above what would otherwise be the normal horizontal plane of the belt in the upper run. This further tensions the belt, and sets up a vertical force urging the belt and shanks downward against the edges 86 and 88, to precisely set the vertical position of the type faces 29 as they advance past the printing positions.

The belt construction enables utilization of a position indicator 106 in any of selected openings 56 between each-of a plurality of fonts of type faces 29 which belt 12 is adapted to accommodate. The indicator has the same cross-sectional dimensions, when viewed in FIG. 5, as a shank 60, and may be of sufficient length to project through sides 57 and 58 when disposed in an aperture 56.

The indicator is adapted to actuate a sensor (not shown) for designating the relative position of belt 12, or of any die face carried from the belt. The sensor (not shown) may be electrical or mechanical or operate electromagnetically, for example, in a manner illustrated in the electrical scheme of the copending application of Ronald S. Denley, Ser. No. l5'3,3l2, filed June l5, l97 l and assigned to the assignee of the present application. No claim is made herein to any sensing combination or to a combination utilizing intelligence sensed for positioning of the belt. However, as a feature of the present invention, no font of type faces 29 or set of pallets 28 requires placing at any given or specific section of the belt. Thereby, a requirement for skilled operators to attend font replacement is obviated if indicators 106 are disposed at opposite ends of such font or pallet set. The only care required to be exercised by an operator in pallet set placement is that type faces 29 be placed at the proper side 58 of the belt, and that the type faces within a font or set be arranged in a proper sequence in the belt segment which they will occupy.

As many modifications in the described construction could be conceived, and as many widely different embodiments could be made without departing from the spirit and scope of the claims, it is intended that all matter contained in the accompanying specification shall be considered as illustrative only and not in a limiting sense.

We claim:

1. An improved belt printer of the class wherein a plurality of type members are carried by a driveable endless belt for continuous horizontal movement with the belt past a printing station when the belt is running, wherein the improvement comprises:

a plurality of type pallets comprising the type members, the pallets having rectangular shanks of a length greater than the width of the belt;

means for mounting the type pallets to the belt for horizontal sliding'movement with respect to the belt in a direction transverse to the direction of belt movement past the printing station, the belt being formed of elastomeric material and provided with a plurality of equally spaced, transverse rectangular apertures extending through the belt and within which the shanks are slidably received so that type faces formed at one end of the shanks project from the belt toward the printing station and the opposite ends of the shanks project from the belt on the opposite side, the belt apertures being proportioned to yieldingly grip the shanks while permitting transverse movement to position the pallets and to permit individual removal of the pallets from the belt by. withdrawing them in the transverse direction while the belt is not running; and

means, engageable with successive pallets when the belt is running, for adjusting the positions of the pallets in the transverse direction and for preventing inadvertent detachment of the pallets from the belt while running, the adjusting means including a pair of fixed camming bars mounted adjacent to the belt in advance of the printing station, each camming bar being positioned to engage one end of an incorrectly positioned pallet and tapered to slide the pallet transversely of the belt toward the desired transverse position, and further including a backstop bar provided along the opposite side of the belt at the printing station for stopping pallet movement during printing and precisely positioning the pallets in the transverse direction.

2. An improved belt printer as recited in claim 1, further comprising:

a pair of vertical-positioning rails mounted on opposite sides of the belt and extending in advance of and along the printing station, the positioning rails being positioned to engage the under surfaces of the advancing shanks in sequence, on opposite sides of the belt, in advance of the printing station and being tapered to elevate each pallet in sequence to a desired vertical position for printing at the printing station, the belt following the .course of the pallets due to engagement of the shanks with the surfaces of the apertures in the belt; and

means for tensioning the belt so that the belt exerts a force urging the shanks against the positioning rails.

3. An improved belt printer of the class wherein a plurality of type members are carried by a driveable endless belt for continuous horizontal movement with the belt past a printing station, wherein the improvement comprises:

a plurality of type pallets comprising the type members;

means for mounting the type pallets to the belt so that portions of the pallets extend outward from the belt on opposite sides thereof in a direction transverse to the direction of belt movement; and

means, engageable with portions of successive pallets on opposite sides of the belt, for vertically positioning the pallets as they approach the printing station, the positioning means comprising a pair of vertical-positioning rails mounted on opposite sides of the belt and extending in advance of and along the printing station, the positioning rails being positioned to engage under surfaces of the advancing pallets in sequence, on opposite sides of the belt, in advance of the printing station and being tapered to elevate each pallet in sequence to a desired vertical position for printing at the printing station, the pallets being engaged with the belt so that the belt follows the course of the pallets, and further comprising means for tensioning the belt so that the belt exerts a force urging the pallets against the positioning rails.

4. An endless belt printer of the class having type elements carried by an endless belt for horizontal movement therewith in a printing course past a printing position, characterized by:

a. the type elements comprising type pallets, each having a type face secured to an elongated shank, the shanks being mounted in apertures formed through the belt and having lengths such that end portions of the shanks project from the belt on each side of the belt in a horizontal direction perpendicular to the direction of belt movement in the printing course; and

b. means, engaging only portions of the shanks on both sides of the belt, for supporting and elevating the pallets prior to the printing course and for supporting and vertically positioning the pallets throughout the printing course in a predetermined horizontal printing line, the belt being unsupported in the printing course except for the means engaging the shanks of the pallets.

5. A printer as recited in claim 4, wherein:

the belt is supported and rotated by parallel rollers mounted for rotation about horizontally aligned, spaced horizontal axes so that the belt has an upper generally horizontal run comprising the printing course and a lower horizontal run comprising a return course; and

the engaging means, by elevating the pallets, elevates the belt in the upper run above its normal line of travel between the rollers.

6. A printer as recited in claim 4, further comprising means for maintaining the pallets stationary, with respect to the belt during the printing operation.

7. A printer as recited in claim 4, wherein: the positioning means comprises a pair of camming rails mounted in the path of movement of the shanks so as to engage the shanks, from beneath, on opposite sides of the belt as the pallets approach the printing position and to elevate the pallets to a desired horizontal printing course level; and further comprising means for tensioning the belt so as to exert a force uring the pallet shanks downward against the camming rails so that the pallets follow the course set by those rails.

8. A printer according to claim 7, wherein said printing course is horizontal along an upper course of said belt, and said camming rails comprise the legs of a U- shaped channel member arranged below said upper course and having its edges disposed for engaging said shanks and vertically adjusting the type faces for printing.

9. A printer according to claim 7, wherein the shanks are rectangular and are arranged with a flat surface downward and horizontal in the printing course, which downward flat surface rides along the edges of the channel prior to and in the printing course.

10. A printer as recited in claim 4, wherein:

the belt is formed of elastomeric material and the size of the apertures is such that the walls of the apertures frictionally grip the pallet shanks to releasably maintain the pallet positions once set, but with such force that the pallets can be moved in the apertures to permit removal and replacement; and

further comprising transverse camming means, mounted in advance of the printing position, for engaging the ends of incorrectly positioned pallets and sliding them in the apertures toward their proper positions for printing.

11. A printer according to claim 10, wherein the transverse camming means comprises fixed inner and outer bosses, disposed on opposite sides of the path of movement of the pallets toward the printing course, said bosses being arranged and tapered for engaging the ends of incorrectly positioned pallets and moving them transversely of the belt for positioning the type faces at an approximate position transversely of said carrier for printing.

12. An endless belt printer of the class having type pallets mounted in apertures in a belt of elastomeric material, characterized by:

a. the type elements comprising type pallets, each having a type face secured to an elongated shank, the shanks being closely received in the belt apertures and having lengths such that end portions of the shanks project from each side of the belt, the size of the apertures being such that the walls of the apertures frictionally grip the pallet shanks to releasably maintain the pallet positions once set, but with such force that the pallets can be moved in the apertures to permit removal and replacement; and

b. camming means, mounted in advance of the printing position, for engaging the ends of incorrectly positioned pallets and sliding them in the apertures toward their proper positions for printing.

13. A printer as recited in claim 12, wherein:

the pallets have rectangular shanks of a length greater than the width of the belt; and

the apertures in the belt comprise a plurality of equally spaced, transverse rectantular apertures extending through the belt and within which the shanks are slidably received so that type faces movement of the pallets toward the printing course, said bosses being arranged and tapered for engaging the ends of incorrectly positioned pallets and moving them transversely of the belt for positioning the type faces at an approximate position transversely of said carrier for printing. 

1. An improved belt printer of the class wherein a plurality of type members are carried by a driveable endless belt for continuous horizontal movement with the belt past a printing station when the belt is running, wherein the improvement comprises: a plurality of type pallets comprising the type members, the pallets having rectangular shanks of a length greater than the width of the belt; means for mounting the type pallets To the belt for horizontal sliding movement with respect to the belt in a direction transverse to the direction of belt movement past the printing station, the belt being formed of elastomeric material and provided with a plurality of equally spaced, transverse rectangular apertures extending through the belt and within which the shanks are slidably received so that type faces formed at one end of the shanks project from the belt toward the printing station and the opposite ends of the shanks project from the belt on the opposite side, the belt apertures being proportioned to yieldingly grip the shanks while permitting transverse movement to position the pallets and to permit individual removal of the pallets from the belt by withdrawing them in the transverse direction while the belt is not running; and means, engageable with successive pallets when the belt is running, for adjusting the positions of the pallets in the transverse direction and for preventing inadvertent detachment of the pallets from the belt while running, the adjusting means including a pair of fixed camming bars mounted adjacent to the belt in advance of the printing station, each camming bar being positioned to engage one end of an incorrectly positioned pallet and tapered to slide the pallet transversely of the belt toward the desired transverse position, and further including a backstop bar provided along the opposite side of the belt at the printing station for stopping pallet movement during printing and precisely positioning the pallets in the transverse direction.
 2. An improved belt printer as recited in claim 1, further comprising: a pair of vertical-positioning rails mounted on opposite sides of the belt and extending in advance of and along the printing station, the positioning rails being positioned to engage the under surfaces of the advancing shanks in sequence, on opposite sides of the belt, in advance of the printing station and being tapered to elevate each pallet in sequence to a desired vertical position for printing at the printing station, the belt following the course of the pallets due to engagement of the shanks with the surfaces of the apertures in the belt; and means for tensioning the belt so that the belt exerts a force urging the shanks against the positioning rails.
 3. An improved belt printer of the class wherein a plurality of type members are carried by a driveable endless belt for continuous horizontal movement with the belt past a printing station, wherein the improvement comprises: a plurality of type pallets comprising the type members; means for mounting the type pallets to the belt so that portions of the pallets extend outward from the belt on opposite sides thereof in a direction transverse to the direction of belt movement; and means, engageable with portions of successive pallets on opposite sides of the belt, for vertically positioning the pallets as they approach the printing station, the positioning means comprising a pair of vertical-positioning rails mounted on opposite sides of the belt and extending in advance of and along the printing station, the positioning rails being positioned to engage under surfaces of the advancing pallets in sequence, on opposite sides of the belt, in advance of the printing station and being tapered to elevate each pallet in sequence to a desired vertical position for printing at the printing station, the pallets being engaged with the belt so that the belt follows the course of the pallets, and further comprising means for tensioning the belt so that the belt exerts a force urging the pallets against the positioning rails.
 4. An endless belt printer of the class having type elements carried by an endless belt for horizontal movement therewith in a printing course past a printing position, characterized by: a. the type elements comprising type pallets, each having a type face secured to an elongated shank, the shanks being mounted in apertures formed through the belt and having lengths such that end portions of the shanks project from the belt on each side of the belt in a horizontal direction perpendicular to the direction of belt movement in the printing course; and b. means, engaging only portions of the shanks on both sides of the belt, for supporting and elevating the pallets prior to the printing course and for supporting and vertically positioning the pallets throughout the printing course in a predetermined horizontal printing line, the belt being unsupported in the printing course except for the means engaging the shanks of the pallets.
 5. A printer as recited in claim 4, wherein: the belt is supported and rotated by parallel rollers mounted for rotation about horizontally aligned, spaced horizontal axes so that the belt has an upper generally horizontal run comprising the printing course and a lower horizontal run comprising a return course; and the engaging means, by elevating the pallets, elevates the belt in the upper run above its normal line of travel between the rollers.
 6. A printer as recited in claim 4, further comprising means for maintaining the pallets stationary, with respect to the belt during the printing operation.
 7. A printer as recited in claim 4, wherein: the positioning means comprises a pair of camming rails mounted in the path of movement of the shanks so as to engage the shanks, from beneath, on opposite sides of the belt as the pallets approach the printing position and to elevate the pallets to a desired horizontal printing course level; and further comprising means for tensioning the belt so as to exert a force uring the pallet shanks downward against the camming rails so that the pallets follow the course set by those rails.
 8. A printer according to claim 7, wherein said printing course is horizontal along an upper course of said belt, and said camming rails comprise the legs of a U-shaped channel member arranged below said upper course and having its edges disposed for engaging said shanks and vertically adjusting the type faces for printing.
 9. A printer according to claim 7, wherein the shanks are rectangular and are arranged with a flat surface downward and horizontal in the printing course, which downward flat surface rides along the edges of the channel prior to and in the printing course.
 10. A printer as recited in claim 4, wherein: the belt is formed of elastomeric material and the size of the apertures is such that the walls of the apertures frictionally grip the pallet shanks to releasably maintain the pallet positions once set, but with such force that the pallets can be moved in the apertures to permit removal and replacement; and further comprising transverse camming means, mounted in advance of the printing position, for engaging the ends of incorrectly positioned pallets and sliding them in the apertures toward their proper positions for printing.
 11. A printer according to claim 10, wherein the transverse camming means comprises fixed inner and outer bosses, disposed on opposite sides of the path of movement of the pallets toward the printing course, said bosses being arranged and tapered for engaging the ends of incorrectly positioned pallets and moving them transversely of the belt for positioning the type faces at an approximate position transversely of said carrier for printing.
 12. An endless belt printer of the class having type pallets mounted in apertures in a belt of elastomeric material, characterized by: a. the type elements comprising type pallets, each having a type face secured to an elongated shank, the shanks being closely received in the belt apertures and having lengths such that end portions of the shanks project from each side of the belt, the size of the apertures being such that the walls of the apertures frictionally grip the pallet shanks to releasably maintain the pallet positions once set, but with such force that the pallets can be moved in the apertures to permit removal and replacement; and b. camming means, mounted in advance of the printing position, for engaging the ends of incorrectly positioned pallets and sliding them in the apertures toward their proper positions for printing.
 13. A printer as recited in claim 12, wherein: the pallets have rectangular shanks of a length greater than the width of the belt; and the apertures in the belt comprise a plurality of equally spaced, transverse rectantular apertures extending through the belt and within which the shanks are slidably received so that type faces formed at one end of the shanks project from the belt toward the printing station and the opposite ends of the shanks project from the belt on the opposite side.
 14. A printer according to claim 13, wherein the transverse camming means comprises fixed inner and outer bosses, disposed on opposite sides of the path of movement of the pallets toward the printing course, said bosses being arranged and tapered for engaging the ends of incorrectly positioned pallets and moving them transversely of the belt for positioning the type faces at an approximate position transversely of said carrier for printing. 